ARTICLE
Current
distribution~status and patterns of spread of the Eurasian beaver Castor fiber, and the ilnplications for lnanagelnent
Duncan J. Halley
&Frank RoselI
DuncanJ. Halley, Department ofConservation Biology, Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway (d [email protected])
Frank Rose!l, Department ofEnvironmental and Health Studies, Telemark University College, N-3800 Bo iTelemark, Norway ([email protected])
Abstract
Redllced to 1200 animals in 8 small refllgia by the end of the 19th century, natura I spread and reintroductions have led to a powerflll recovery in Eurasian beaver (Castor fiber L. ]758) range and populations. The minimum popu1ation is now 592 000 animals, of which c.40% are found in Russia. In Europe, beaver are common and widespread in European Russia, Scandinavia, the Baltic states and Belarus; scattered populations are now established in al!
other countries with the exception of the Caucasus, Iberia, Italy, the southern Balkans, and the British Isles. Further reintroductions are continuing. Itseems clear that beaver will within a few decades once again be a tolerably common mammaI in suitable habitat over most of its former European range. Patterns of spread and population deve10pment indicate that populations should be managed at the watershed scale.
Key words: Castor fiber, distriblltion, status, poplllafions, management Introduction
Formerly widespread throughout l11uch of the Palaearctic region, Eurasian beaver Castor fiber (L. ]758) popu!ations were reduced through overhunting to c. 1200 animals, in eight isolated populations, by around the end of the 19th Century. Since the 1920s, effective protection of these remnants, the resultant natural spread, and widespread reintroductions have led to a powerfu l recovery in both range and popu lation.
Population status
The minimum population estimate in 2000 is 592 000 individuals. There are a1so c. 12 500 North American beaver C. canadensis established in Finland and Russian Karelia (Ennala et al.
1999); however, other populations of canadensis introduced to Austria, Poland and france appear to be extinct (Sieber pers. comm.; Moutou 1997).
Populations are now established throughout Europe, witll the exception of the British Isles, Iberia, Italy, and the southern Balkans. Habitat occupied ranges from wilderness areas to intensively managed landscapes with dense human populations, and from \Varm temperate to sllbarctic climates. Reintroductions are continuing. Considerable fmther expansion of both range and population, especially in western Europe and the lower Danube bas in, can be expected. Jf current trends continue, C. .fibei' will within a few decades be a fairly common mamma] throughout l11uch of Eumpe.
Halley DJ. & Roseil, F. 200l. Current d istribution, status and patterns of spread of the Eurasian beaverCosfor/iDer,
and the il1lplicatiol1s
ror
management. Pages 15-24 in: Czech, A. & Schwab, G. (eds): The European Beaver ;n ann\' millennium. Proceeclings or 2nd European Beaver Symposium, 27-30 Sept. 2000, Bialo\\'ieza, Poland. Carp<llhian Heritage Society, Krakow.1~
,"
..~
Duncan
J.Halley
&Frank Rosell
Patterns of spread and population development
Following initial establishment on a watershed, populations typically show a pattern of rapid range extension, followed only later by rapid population growth (Fig. l). There is strong selection for high-quality habitat at this stage, which appears to explain the rapidity of range extension. Later (on average, 34 years post-colonisation in Sweden), populations go into decline as marginal habitat is occupied and then exhausted (Fig. 2). The period of peak and declining populations often cOlncides with a peak in conflicts with human landuse interests, as marginal habitats are more likely to require extensive modification by beavers.
o
20, I
km
"*
F;eintroduction,. Colonised 1950 A Colonised 1960 o Colonised 1970 lJ. Colonised 1980
\
fig. l. P:,Ucrns of spread of beavers rccolonising V~in11land provincc. Swcdcn. Terrain is ilat to mildly hilly and hc:\vilv'.\-'oded. Watershcd dividcs are shown by bold lines. Dates and loc"lions of reinlrodllctiolls are indicalcd.
Beave," -'Fc,d very rapidiy throllghout walersheds aller initial recolonisation, wilh inlilling lhcrealtcr. Watcrshcd divides. !iU\\c:;ver, signil"ic<1ntly slowed range c\pansion. figure adapted from J-larll1lan (1994).
Current distribution, status and patterns of spread of the Eurasian beaver Castor fiber, and the implications for management
'1 O 20 30 40 50 50
Years since tlr~;t colonisation
o o
I!'j
1976
o
19:::7
----.
E
0.75
~ CJ
--
(j)(j)CDc
0.5
o ou
'---"
>-.
-
UlC O.<-~')r- oCDFig. 2. Changes in loeal beaver populatioll densities in Varmland, Sweden, related to time sinee eolonisation. Figure adapted from Hartman (1994).
Fig. 3. Distribution ofbeavers in Trondheim Byneset in 1998. Filled black eireles represent the eentres ofactive home ranges; hollow cireles indieate abancloned home ranges. Beaver were reintrodueed in 1975 and by 1998 had colonisecl three of the six major streill11 systems. Eaeh of the three largest uneo!onised stream systems contaill suffieient habitat for severaI beaver eo10nies, but as ~'et remain unoeeupiccl, although clemly marginal sites on the other systems are in lise or have been abandoned.
17
Duncan 1. Halley & Frank RoselI
Barriers to spread
Even in areas with short overland distances between suitable habitats and favourable terrain, watershed divides fonn a clear barrier to population spread (Fig. l & 3). Where a significant physical barrier between suitable habitat on different watersheds exists, such as mountains (e.g.
Switzerland) or intensive farmland (e.g. Elez River, Brittany), it may be strongly isolating.
Beaver only succeeded in establishing on a watershed adjacent to the Elez in 1997, 28 years after initial reintroduction (Stevenson pers. comm.)
Man-made dams and barrages have also been shown to constrain or prevent population spread within a river system, e.g. on the Rhone and Danube (Office Nationale de la Chasse 1997; Pachinger & Hulik 1998). Solutions include the construetion of "beaver ladders" around balTages (Office Nationale de la Chasse 1997).
Management implications
Beaver populations and distribution should nonnally be managed at the watershed scale. A major exception is that sections ofwatersheds may be manageable in isolation where man-made dams act as barriers to beaver dispersal. Populations can be regulated, and conflicts with human land uses minimised, through the introductioll of a controlled harvest (e.g. through sport hunting). This should be introduced during the rapid increase phase of population growth (Ha11mann 1994).
Early provision of interpretation and public viewing opportunities has been a feature of many recent reintroductions. This provides benefits in the form of public enjoyment, enhancement of the local economy through wildlife tourism, and the fostering of positive attitudes to beavers.
Acknowledgments
Many beaver researchers throughout Europe kindly responded to our requests. for inform3iion. In pal1icular, we would like to thank A. Stevenson; S. Asbirk; O. BosZE~r; K.
Bevanger; S. Capt; A. Czech; R. Dennis; M. Gaywood; M. Grubesic; G. Hartman; V. Kostkan;
P. Lahti; R. Liobis; P. Rouland; G. Schwab; J. Sieber; A. Ulevicius & C. Winter. \Ve would like to thank G. Hartman for allowing us to adapt figures on range extension and population grO\vth/decline from data published in his doetoral thesis on beaver population development in Sweden .
lOO-130
150 300 24,000
o
1998-99 200] -02 1996-98 1991-92, 1996
? 1922
ISS7?
17thcentury 1848 rClllnant
~'~_.''-'-
..
"I~,tl~~",!,~,~7 ).',~,1.~l~1~'1...
~~~.~,>e!~~~"!l!,,2<!:~~~!L~L~~!L~,~~22,1:s.a,~.sr,~.,ifE,~!.~~,!r,~t;.!:t.~~!E~!~l~,~~L!~:'_.l:I~~.~~~~~:~.~!..
~g2.:]L..
~,~,~~.L"",""",""Country Extirpation Proteetion Rcintroduetion Present Rcfercn-:cs
.".-.." ,,',._ ., ' .." ' .. __._ '._ _'__,,_~t.:~~~~~E~!.~?!,?E~.~~!:~,.._,.r2P~~~,~is!,~~~~.~..__"_.,"" ,'_,, ,,', ",..,_,.""'._,..
Austri" 1869 1970-90 >1300 Kollar &. Seiter ([ 990),.
Sicber (pers. COIllIl1.)
Djoshkin& Safonov (1972), Safollov &
Savc!icv(!999) Sehwab (pers.COI11I11.),
Libois (pers.COI11I11.)
Sehwab (pers. eOll1m) Grubesie (pers. eomm) Kostkan&Lehky (1997), Kostkan (1999), KoslKail (pers
CUlTent distribution, status and patterns of spread of the Eurasian beaver Castor fiber, and the imp!ications for management
Denmark c.500 BCI 1999 18 Skov- og Naturstyrelsen
1999; Asbirk (2000&
pers. COI11I11.)
England 12th century Under investigation O Macdonald et al.
(1995); Tattersall (pers. COl11m.. )
Estonia 1841 1957 l 1,000 Laanetu (1995),
Ulevicius (pers.
COI11I11.), Til11l11 (Estol1ian Envi ronl11ental 1nfonnation Centre) (pers. COl11m.)
Finland 1868 1868 1935-37,1995 1500 Ermalael al. (1989),
Lahti (1995), Harkbnen (1999), Harkbnen (pers.
co111 111.)
France rel11nant 1909 1959-95 7000-10,000 Richard (1986),
Office Nationale de la Chasse (1997), Rouland (Office Nationale de la Chasse) (pers.
con1111.), Dennis (pers.
COI11I11.)
Germany rel11nant 1910 1936-40, 8000-10,000 Schwab el al. (1994),
1966-89, Macdonaldet al.
1999-2000 (1995), Schwab (pers.
comm.).
HlIngary 1865 1980-2000 70 Kollar&Seiter
(1990), Bozscr(pers.
COIIIIII.)
Jta1y 1541 proposed O Nolet (1996)
Kazakhstan ? 1000 Djoshkin & Safonov
(1972);SaveUev
&
Safonov (1999);
Safonov & Save1iev (1999)
Latvia 1830s 1927-52, >100,000 Balodis (1992, 1994,
1975-84 1995,1997,1998);
Ozolins& Bau!11tlnis 2000
Lithuania 1938 1947-59 32,000-50,000 Mickus (1995),
Uleviciuset of.
(1999), BalciaLlskas et al. (1999);
Ulevicius (2000)
Mongolia& rCl11nant ? 1959-85 800 Lavrov & LlI Hao-
China TSllan (1961), LaVfOV
(1983), Stubbe&
Dawaa (1983,1986)
19
Duncan
J.Halley
&Frank RoselI
Net1Jerlands 1826 J988-2000 c.140
Norway remnant 1845 1925-32, >50,000
1952-65
Poland 1844 1923 1943-49, 17,000
1975-86
Romania
Russia
Scotland
Slovenia Slovakia
Swedcn
Switzerlaiid
Turke)' Ukrain('
1824?
remnant
16th century
? 1851
1871
1820
remnant?
remnant
1922
?
1873
1922
1998-99
1927-33, 1934-41, 1946-64
2002?
1999 1995
1922-39
1956-77
?
>28
232,000- 300,000
o
<62
>500
>100,000
>350
? 6000
Nolet (1994), Djikslra &. Niewold (pers. comm.) Bevanger 1995;
RoselI &. Pedersen (1999)
Zurowski &.
Kasperczyk (1986, 1988),
Zurowski (1992), Macdonald et al.
(1995), Czech 1999,
Dzi~ciolowski &.
Gozdziewski 1999, Czech (pers. comIn.) Troidl &. 10nescll (1997), Schwab (pers.
cOl1lm.)
Djoshkin &. Safonov (1972), Lavrov (1983), Saveljev &.
Safanov (1999), Safonov &. Saveliev (1999), Dezhkin (1999)
Kitchemer &. Comoy 1997; Scottish Natural Heritage (2000) Grubesic (pers. comm).
Pachinger& Hlllik . (1999); Yalachovic (1997), Dllha &.
Ma.ilan (1997) Freyc (1978), I-Iartman (1994a,
1995 b); pers. comm·.
Stocker (1985), Macdonald et al.
(1995), Winter (1997), S. Capt, Centre Suissede Cartographie de la falme(pers. cOl11m.) Savclycv (2000) Djoshkin &. Salonov (1972), Lavrov&
Lavrov (1986), Salonov
&. Savc!icv l
Bascd (F" .subfossil rel11ains. Philological cvidence from placenal11es suggests a remnant may have survivcd as late as the! !ti;c':iltury (Klein 1999).
2B)" na'.u;,,:: spread from the Croatian reintrodllction on the Sava river
Es[o,,; .:.11 - 1957 11,000 Laanetu (1995), Ulevicills (pers. COI11I11.), Timill (Estonian Environmcntal Information Ccnlrc)(pu·s. COI11I11.)
Current distribution, status and patterns of spread of the Eurasian beaver Castor fiber, and the implications for management
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23
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